1. Field of the Invention
The present invention relates to a liquid ejection apparatus.
2. Description of the Related Art
Japanese Unexamined Patent Application Publication No. 2011-207025 discloses an ink-jet printer including a maintenance mechanism that allows switching among a suction purge for recovery from an ejection failure by sucking ink from the nozzles of an ink jet head, an exhaust operation for recovery from an ejection failure caused by the growth of bubbles by sucking ink together with the bubbles from an exhaust channel in a subtank for supplying ink to the ink jet head, and an ink discharge operation for discharging ink remaining in a tube connecting a suction pump for use in the suction purge and the exhaust operation and a waste liquid tank. This ink jet printer executes the liquid discharge operation just before a suction purge (a liquid sucking operation) in a periodic suction purge (a sucking process). This allows the suction purge to be executed after thickened ink remaining in the tube is discharged. This prevents the tube from coming out of the pump due to an increase in the pressure in the tube when the suction purge is executed.
The ink-jet printer disclosed in Japanese Unexamined Patent Application Publication No. 2011-207025 executes the liquid discharge operation just before the suction purge of the periodic suction purge. The periodic suction purge is executed every one or two months, for example. The liquid discharge operation is executed also after the periodic suction purge, but a little ink sometimes remains in a cap after completion of the liquid discharge operation because the cap is increased in size as a result of a move to large-sized liquid ejection heads for high-speed printing. The ink remaining in the cap collects to the tube connecting the suction pump and the waste liquid tank and a tube connecting the suction pump and the cap (connecting channels). The ink (liquid) collecting in the tubes increases in viscosity, so that the ink in the tubes cannot be sucked in a suction purge. If the suction purge etc. are not performed, during which the ink does not flow in the tubes for a long time, so that the viscosity of the ink increases, the ink cannot be discharged even if the liquid discharge operation is executed, and the clogging of the tubes cannot be resolved. Thus, no actual suction purge or exhaust operation can be executed even if a suction purge or an exhaust operation is executed.